The first incident involved a blood test ordered in 2013 for a patient using the company’s proprietary “Edison” lab machine. The lab worker assigned to the test found problems that indicted accuracy problems with the device. When the lab worker told superiors, a research and development employee came to the lab and deleted the data.

In the second incident cited by the Journal’s John Carreyou, an employee sent an email to CEO Elizabeth Holmes in 2014 alleging that the company had “cherry-picked” data when comparing the “Edison” machines to traditional blood-testing machines to make the machines look more accurate.

From the report:

For one test, the device’s accuracy rate increased sharply after some information was deleted and manipulated, the employee wrote. Edison machines also allegedly failed daily quality-control checks often.

Theranos spokesperson Brooke Buchanan told the Journal she didn’t believe the first incident ever happened. In the second incident, Buchanan put the blame on the employee, who she said was too inexperienced to “make these types of comments.”

This isn’t the first time Theranos has run into trouble in the past few months.

Earlier this month, The Wall Street Journal reported that regulators for the Food and Drug Administration and Centres for Medicare and Medicaid Services are currently investigating two separate complaints by former employees of the startup.

The first complaint alleged that the company instructed employees to test patients’ blood using Theranos’ devices even though there was evidence of “major stability, precision, and accuracy” issues.

The second complaint alleged that a study submitted by Theranos last year for a herpes test was extremely problematic because of improper research protocols.